1. Field of the Invention
The present invention relates to a device for placing a structural element in a cable installation conduit in order to sub-divide it. It relates especially to a method to position this structural element by means of the device of the invention.
Many networks presently consist of unitary conduits in order to obtain the circulation therein of a fluid or to take a cable for the conveyance of power or telecommunications signals.
2. Description of the Prior Art
The present-day optical fiber cables used in the new optical fiber telecommunications networks are highly dense (with high-capacity micro-sheathed or ribbon cables) or again very compact for low-capacity cables such as multiple-core fiber cables for example.
In the development of these new optical fiber telecommunications networks, FRANCE TELECOM has envisaged the optimizing of the available volume in the cable installation conduits by developing a multi-alveolate structural element designed to sub-divide a conduit. The fitting of such a structural element into a conduit has been envisaged in order to lay a larger number of cables in a conduit and to make them independent of one another, thus preventing the strains induced by the laying of a new cable from getting applied to cables already positioned in the structural element.
Thus, the French patent FR 2 730 101 describes a flat-conditioned multi-alveolate structural element designed to divide a cable installation conduit into several sections. The development of this structural element is recent. Hence, no device or method has yet been seriously designed to position it in a cylindrical conduit. Until now, the structural element has been given a cylindrical shape by having its ends clipped together, and it is cold-inserted into the conduit without any special precautions being taken.
The fact of keeping the structural element in its cylindrical shape (by clipping) leads to its embrittlement. The structural element tends to become more easily breakable, and its resistance to mechanical impact as well as to torsional and bending forces is greatly reduced. Furthermore, the fact that the structural element is cold-inserted into the conduit without any preliminary action on it causes the appearance of major frictional forces. All these problems thus prevent the laying of the structural element over great lengths. The laying lengths are indeed far smaller than the minimum required distance which is 300 meters and corresponds to the distance between two underground chambers.
The present invention makes it possible to overcome the drawbacks of the prior art. For this purpose, it proposes a simple and low-cost device enabling the placing of a structural element in a cylindrical conduit over a great length without any embrittlement or deterioration of this structural element.